Micro-optical couplers are widely used in a variety of applications including data communications, telecommunications, and sensing. Such micro-optical couplers typically comprise one or more optical functional elements which selectively transmit, reflect, attenuate, filter, split, combine, or manipulate the optical signals propagating within them together with an input and output optical systems for guiding light to/from the functional elements from/to the optical fibers that transmit the optical signals within the systems that the micro-optical couplers form part of. Micro-optical devices also allow integration of two or more elements within the same component thereby reducing component count, cost, footprint etc. For example in optical amplifiers micro-optical devices may combine a power tap, wavelength division multiplexer (WDM), gain flattening filter (GFF), and optical isolator. Typically, the functional optical elements are thin film filters, micro-optical isolator cores, and birefringent/polarizing sheets whilst the input and output optical systems usually comprise a collimating lens, as well as input and output optical waveguides (usually optical fibers).
Typical prior art micro-optic coupler designs require that only small and even gaps exist between all the cylindrical surrounding surfaces that are bonded together. Also, from cost and mechanical design requirements the active alignment processes employed in such prior art micro-optic couplers should avoid the requirements for active angular alignment. Such a requirement requires that the design provides effective means to compensate for the inherent optical path walk-off that occurs within such micro-optical couplers, while keeping all the mechanical parts within the device structure fitting tightly to each other to minimize solder and/or epoxy (glue) lines.
The performance, reliability, and cost of the optical couplers depends heavily on their design and packaging technologies. A need still exists in the art of design and manufacturing of optical coupler devices to provide superior performance, improved reliability and reduced cost simultaneously whilst addressing issues such as walk-off. Such improvements arising from the inclusion of asymmetric optical elements within the optical path rather than the circularly symmetric optical elements within the prior art.
Beneficially embodiments of the invention provide a multi-port optical coupler design platform that can be used for a range of micro-optic couplers including, but not limited to, wavelength division multiplexers (WDM), tap coupler, gain flattening filter, isolator and compact hybrid devices with multiple functions. The design methodology is compatible with epoxy-free optical path, hermetic assemblies, and epoxy-in-path designs according to the requirements for environmental performance, reliability, cost, etc.
It is a further object of this invention to provide a micro-optic coupler design that requires fewer parts, allows the functional optical elements to be pre-assembled and the optical fibers assembled thereafter such that automated optical pre-screening of the functional optical assemblies can be performed prior to the assembly of the optical fibers which is typically a labour intensive element impacting the overall cost of the micro-optic couplers.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.